Modern flight deck displays (or cockpit displays) for vehicles (such as an aircraft) display a considerable amount of information, such as vehicle position, speed, altitude, attitude, navigation, target, and terrain information. In the case of an aircraft, most modern displays additionally display a flight plan from different views, either a lateral view, a vertical view, or a perspective view, which can be displayed individually or simultaneously on the same display. The perspective view provides a three-dimensional view of the vehicle flight plan (or vehicle forward path) and may include various map features including, for example, weather information, terrain information, political boundaries, and navigation aids (e.g., waypoint symbols, line segments that interconnect the waypoint symbols, and range rings). The terrain information may include situational awareness (SA) terrain, as well as terrain cautions and warnings which, among other things, may indicate terrain that may obstruct the current flight path of the aircraft. In this regard, some modern flight deck display systems incorporate a synthetic terrain display, which generally represents a virtual or computer simulated view of terrain rendered in a conformal manner. The primary perspective view used in existing synthetic vision systems emulates a forward-looking cockpit viewpoint. Such a view is intuitive and provides helpful visual information to the pilot and crew.
The integrity of the synthetic terrain display is limited by the integrity of the information pre-stored in the database utilized to render the terrain. Accordingly, synthetic vision systems often utilize onboard imaging devices to augment or enhance the forward-looking cockpit view. For example, an enhanced vision system may use an infrared and/or millimeter wave video camera to sense objects and/or terrain features and render real-time imagery based on the sensed objects and/or terrain features that is overlaid onto the synthetic terrain display. In this manner, the enhanced vision system may provide higher integrity terrain imagery as well as imagery corresponding to various non-terrain features, such as other vehicles and buildings, which are not represented by a priori databases. These enhanced synthetic vision systems are particularly useful when operating a vehicle or aircraft in instrument meteorological conditions (IMC) or conditions of reduced visibility, such as, for example, whiteout, brownout, sea-spray, fog, smoke, low light or nighttime conditions, other inclement weather conditions, and the like. It is desirable that these enhanced vision systems be perceived quickly and intuitively without detracting from the situational awareness of the pilot and/or crew.